JPH081411A - Cutting tool made of surface-covered tungsten carbide base cemented carbide having excellent in-layer adhesion of hard covered layer - Google Patents

Abstract

PURPOSE:To improve the in-layer adhesion of the hard covered layer by providing the structure of the aluminum oxide layer on the top layer mainly consisting of the kappa type crystal. CONSTITUTION:A hard covered layer of the prescribed mean thickness within 3-30mum consisting of a first layer consisting of TiN having the granular crystalline structure, a second layer consisting of TiCN having the granular crystalline structure, a third layer consisting of TiC having the granular crystalline structure, and a fourth layer consisting of TiCO or TiCNO having the granular crystalline structure, and a fifth layer consisting of Al2O3 having the alpha type crystalline structure is formed on the surface of the cemented carbide base body. The TiCN layer of the second layer is of the longitudinal growing crystalline structure, and the Al2O3 layer of the fifth layer is of the structure mainly consisting of the kappa type crystal. This constitution improves every in-layer adhesion of the hard covered layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a hard coating layer having excellent interlayer adhesion, and therefore exhibits excellent cutting performance over a long period of time when used for cutting, for example, mild steel having a large cutting resistance. The present invention relates to a surface-coated tungsten carbide based cemented carbide cutting tool (hereinafter referred to as a coated cemented carbide cutting tool).

[0002]

2. Description of the Related Art Conventionally, as described in Japanese Patent Publication No. 57-1585 and Japanese Patent Publication No. 59-52703, for example, an entirely homogeneous tungsten carbide based cemented carbide substrate and a binder phase forming component have been used. For example, a tungsten carbide based cemented carbide substrate having a surface portion in which the content of Co or the like is relatively high compared to the inside of the substrate, that is, a surface portion having a binder phase enriched zone (hereinafter, these are collectively referred to as cemented carbide substrate. On the surface of chemical vapor deposition or physical vapor deposition, the first layer of titanium nitride (hereinafter, TiN), the second layer of titanium carbonitride (hereinafter, TiCN), titanium carbide. A third layer (hereinafter, referred to as TiC), a fourth layer made of titanium carbonate (hereinafter, referred to as TiCO) or titanium carbonitride oxide (hereinafter, referred to as TiCNO), and aluminum oxide (hereinafter, referred to as Al). ₂ O ₃ ))
Layer, and further, if necessary, a hard coating layer composed of a sixth layer made of TiN with a predetermined average layer thickness within the range of 3 to 30 μm is mainly used for alloy steel and It is well known that it is used for turning and milling cast iron.

[0003]

On the other hand, in recent years, the use of FA in cutting machines has been remarkable, and in conjunction with the demand for labor saving in cutting work, cutting tools tend to be required to be versatile. For carbide cutting tools, there is no problem if this is used for cutting alloy steel or cast iron, etc.
Particularly when used for cutting mild steel with high cutting resistance, the interlayer adhesion of the hard coating layer is not sufficient, so that the hard coating layer is liable to delamination and chipping, which causes a relatively short service life. At present.

[0004]

Therefore, the present inventors have
From the viewpoints described above, as a result of focusing on the above-mentioned conventional coated carbide cutting tool and conducting a study for improving the interlayer adhesion of the hard coating layer constituting the same, (a) the above conventional coated carbide In the hard coating layer constituting the cutting tool, there is no problem in the adhesion of the first TiN layer to the cemented carbide substrate, but the first TiN layer and the third TiN layer
Adhesion of the second TiCN layer to the second TiC layer, and the fourth TiCO or TiCNO layer and the sixth
The adhesion of the Al ₂ O ₃ of the fifth layer to the TiN layer of the layer is insufficient, and this easily causes delamination or chipping. (B) In the hard coating layer constituting the conventional coated carbide cutting tool, the first TiN layer and the second TiCN layer
Layer, third layer TiC layer, fourth layer TiCO layer and Ti
Ti of the CNO layer and the sixth layer formed as necessary
N layer both have a granular crystal structure, the fifth layer Al ₂ O
₃ layers should have alpha type crystal structure. (C) In the hard coating layer constituting the above conventional coated carbide cutting tool, the second TiCN layer has a vertically elongated crystal structure, and the fifth Al ₂ O ₃ layer mainly has a copper crystal. Assuming that the structure has a structure (preferably, a structure in which a copper type crystal occupies 50% by volume or more, and the balance is an alpha type crystal, or a structure in which a copper type crystal is substantially formed), the resulting hard coating layer has any layer structure. Adhesion is also significantly improved, so even when cutting a work material with high cutting resistance, delamination chipping does not occur and excellent cutting performance is exhibited over a long period of time. (D) The TiCN layer having a vertically elongated crystal structure that constitutes the second layer of the hard coating layer of (c) is divided into a plurality of layers by one or more TiN layers having a granular crystal structure, that is, The Ti is formed on both the upper and lower sides of the TiN dividing layer.
When the structure having the CN division layer is present, the fracture resistance of the cutting edge is remarkably improved particularly in heavy cutting such as high feed cutting and high depth cutting. The research results shown in (a) to (d) above were obtained.

The present invention was made on the basis of the above-mentioned research results, and the first layer of TiN, which is made of TiN having a granular crystal structure, is formed on the surface of the cemented carbide substrate.
Second layer made of N, third layer made of TiC, fourth layer made of TiCO or TiCNO, and fifth layer made of Al ₂ O ₃ having an alpha-type crystal structure, and granular crystals formed as necessary. A coating formed by forming a hard coating layer composed of a sixth layer of TiN having a texture into a predetermined average layer thickness within a range of 3 to 30 μm by using a normal chemical vapor deposition method and / or a physical vapor deposition method. In the cemented carbide cutting tool, the second layer is composed of a TiCN segmented layer having a plurality of vertically elongated crystal structures segmented by one or more TiN segmented layers having a granular crystal structure, and a fifth layer A characteristic feature of the coated carbide cutting tool is that the Al ₂ O ₃ layer of the layer has a structure mainly composed of kappa-type crystals to improve the interlayer adhesion of the hard coating layer.

A TiCN partition layer having a vertically elongated crystal structure, which constitutes the second layer of the hard coating layers constituting the coated cemented carbide cutting tool of the present invention, is disclosed in, for example, JP-A-6-80.
As described in Japanese Patent Publication No. 10, the reaction gas composition: volume%, TiCl ₄ : 1 to 10%, C
H ₃ CN: 0.1 to 5%, N ₂ : 0 to 35%, H ₂ : residual, reaction temperature: 850 to 950 ° C., atmospheric pressure: 30 to 200 torr. On the other hand, a TiCN layer having a granular crystal structure usually has a reaction gas composition: volume%, TiCl ₄ : 1 to 5%, CH
_{4: 2~7%, N 2:} 15~30%, H 2: remainder, reaction temperature: 950 to 1050 ° C., atmospheric pressure: 30～200Torr, is formed by the conditions. Further, the Al ₂ O ₃ layer having a structure mainly composed of a copper-type crystal is composed of a reaction gas: volume% and an Al phase of 1 to 120 minutes in the initial stage.
Cl _3: 1-20%, HCl if necessary: 1-20%
And / or _{H 2 S: 0.05~5%, H} 2: remainder,
Thereafter, AlCl ₃ : 1 to 20%, CO ₂ : 0.5
-30%, if necessary HCl: 1-20% and / or H ₂ S: 0.05-5%, H ₂ : remaining, reaction temperature: 850-1000 ° C., atmospheric pressure: 30-200 torr, conditions Is formed by.

In the hard coating layer constituting the coated cemented carbide cutting tool of the present invention, the TiN layer of the first layer is first deposited on the surface of the cemented carbide substrate, and then the TiCN section layer of the second layer and the TiN layer. It is formed by sequentially vapor-depositing a dividing layer to a fifth Al ₂ O ₃ layer and, if necessary, a sixth TiN layer. When forming the second and subsequent layers, the first layer In some cases, the C component in the cemented carbide substrate may diffuse and form a solid solution in the TiN layer, and in this case, the first layer exists as the TiCN layer after the hard coating layer is formed.

Further, the hard coating layer has an average layer thickness of 3 to 3.
Preferably, the average layer thickness is 3 μm.
If the average layer thickness is less than 30 μm, the chipping resistance will rapidly decrease, and if the average layer thickness exceeds 30 μm, the first layer will not be able to secure desired wear resistance. The average thickness of the TiN layer is 0.1 to 5 μm.
m of the second TiCN partition layer and that of the TiN partition layer are 3 to 20 μm and 0.1 to 5 μm, and the third layer of TiC.
The layer is 1 to 10 μm, the fourth layer of TiCO layer or TiCN
The O layer has a thickness of 0.01 to ₂ μm, and the fifth Al ₂ O ₃ layer has a thickness of 0.
1 to 15 μm, and the sixth TiN layer has a thickness of 0.1 to 5 μm.
An average layer thickness of m is desirable.

[0009]

Next, the coated carbide cutting tool of the present invention will be described in detail with reference to examples. As the raw material powder, a medium-grain WC powder having an average particle diameter of 3 μm and a coarse-grain WC having the same particle diameter of 5 μm
Powder, 1.5 μm (Ti, W) C (weight ratio, same below, TiC / WC = 30/70) powder, 1.2 μm
(Ti, W) CN (TiC / TiN / WC = 24/2)
0/56) powder, 1.3 μm (Ta, Nb) C (T
aC / NbC = 90/10) powder and 1.2 μm
Are prepared, and these raw material powders are blended in the composition shown in Table 1, and wet-mixed for 72 hours by a ball mill.
After being dried, it is press-molded into a green compact having a shape defined by ISO / CNMG120408 (for cemented carbide base bodies A to D) and SEEN42AFTN1 (for cemented carbide base body E),
Cemented carbide base bodies A to E were manufactured by vacuum-sintering the green compact under the conditions shown in Table 1. Further, the cemented carbide substrate B is kept in a 100 torr CH ₄ gas atmosphere at a temperature of 1400 ° C. for 1 hour, and then subjected to a slow cooling carburizing treatment. After the treatment, carbon and carbon adhering to the substrate surface are removed.
By removing o by acid and barrel polishing, a Co-enriched zone having a maximum Co content of 15% by weight and a depth of 40 μm was formed at a position 10 μm from the surface in the surface layer portion of the substrate.
In the cemented carbide substrates A and D, a Co-enriched zone having a maximum Co content of 9% by weight and a depth of 20 μm was formed on the surface layer at a position 15 μm from the surface while being sintered. The remaining cemented carbide substrates C and E have the above C
o There was no formation of enriched zones, and there was an overall homogeneous structure. Further, Table 1 shows that the cemented carbide substrates A to E
Of each sample (Rockwell hardness A scale).

Then, the surfaces of these cemented carbide substrates A to E were subjected to honing, using a conventional chemical vapor deposition apparatus, under the conditions shown in Table 2 under the conditions shown in Table 2 and the compositions shown in Tables 3 to 7 The coated carbide cutting tools 1 to 7 of the present invention and the coated carbide cutting tools 1 to 7 of the related art were manufactured by forming a crystal structure and a hard coating layer having an average layer thickness. Next, regarding the above-mentioned coated carbide cutting tools 1 to 5 of the present invention and conventional coated carbide cutting tools 1 to 5, work material: mild steel round bar, cutting speed: 190 m / min., Feed: 0.41 mm / rev ., Depth of cut: 2 mm, cutting time: 30 min., High-feed continuous cutting test of mild steel, and work material: round bar of mild steel, cutting speed: 190 m / min., Feed: 0.26 mm / rev ., Depth of cut: 4 mm, Cutting time: 40 min., A high-cut continuous cutting test of mild steel was performed, and the flank wear width of the cutting edge was measured in each cutting test. The results of these measurements are shown in Table 8. Further, regarding the above-mentioned coated carbide cutting tools 6 and 7 of the present invention and conventional coated carbide cutting tools 6 and 7, the work material is a square of mild steel, the cutting speed is 240 m / min., The feed is 0.36 mm / blade, Milling of mild steel was performed under the following conditions: depth of cut: 3 mm, cutting time: 40 min, and the flank wear width of the cutting edge was measured. The measurement results are also shown in Table 8.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

[0014]

[Table 4]

[0015]

[Table 5]

[0016]

[Table 6]

[0017]

[Table 7]

[0018]

[Table 8]

[0019]

From the results shown in Tables 3 to 8, the coated cemented carbide cutting tools 1 to 7 of the present invention are not susceptible to delamination or chipping of the hard coating layer despite the cutting of mild steel having high cutting resistance. While it does not occur and shows excellent wear resistance,
Conventionally, the coated carbide cutting tools 1 to 7 clearly show that the interlayer adhesion in the hard coating layer is insufficient, and delamination and chipping occur in the cutting of mild steel, resulting in a relatively short service life. is there. As described above, the coated cemented carbide cutting tool according to the present invention has a hard coating layer having excellent interlayer adhesion, so that it can cut not only alloy steel and cast iron, but also mild steel having a high cutting resistance. Even when used for cutting, excellent cutting performance is exhibited over a long period of time.

Claims (2)

[Claims] 1. A titanium nitride base cemented carbide substrate that is wholly homogeneous, or a titanium carbide base cemented carbide substrate that has a binder phase enriched zone in the surface layer. A first layer made of titanium carbonitride, a second layer made of titanium carbonitride, a third layer made of titanium carbide, and a fourth layer made of titanium carbonate or titanium oxycarbonitride, and a fifth layer made of aluminum oxide having an alpha-type crystal structure. A surface-coated tungsten carbide-based cemented carbide cutting tool comprising a hard coating layer composed of a layer and having a predetermined average layer thickness within the range of 3 to 30 μm, wherein the second layer has a granular crystal structure. The fifth layer of aluminum oxide is composed of a titanium carbonitride partition layer having a plurality of vertically elongated crystal structures divided by one or more titanium nitride partition layers. A surface-coated tungsten carbide-based cemented carbide cutting tool having an excellent interlaminar adhesion with a hard coating layer, characterized in that the layer has a structure mainly composed of copper type crystals. 2. A titanium carbide base cemented carbide substrate that is wholly homogeneous, or a titanium carbide base cemented carbide substrate that has a binder phase enriched zone in the surface layer. A first layer made of titanium carbonitride, a second layer made of titanium carbonitride, a third layer made of titanium carbide, and a fourth layer made of titanium carbonate or titanium oxycarbonitride, and a fifth layer made of aluminum oxide having an alpha-type crystal structure. Layer and a surface-coated tungsten carbide-based cemented carbide cutting formed by forming a hard coating layer composed of a titanium nitride having a granular crystal structure and a sixth layer with a predetermined average layer thickness within the range of 3 to 30 μm. In the tool, the above-mentioned second layer is a titanium carbonitride section having a plurality of vertically elongated crystal structures divided into one or more titanium nitride division layers having a granular crystal structure. Surface-coated tungsten carbide-based cemented carbide having a hard coating layer having excellent interlayer adhesion, characterized in that the aluminum oxide layer of the fifth layer has a structure mainly composed of copper type crystals. Cutting tools.